Imported water consists primarily of water obtained from the State Water Project, LA Aqueduct, and Colorado River. Water retailers purchase imported water from local contractors or regional wholesale water agencies.

State Water Project

The State Water Project (SWP) includes 22 dams and reservoirs, a Delta pumping plant, a 444-mile-long aqueduct that carries water from the Delta through the San Joaquin Valley to Southern California. The SWP begins at Oroville Dam on the Feather River and ends at Lake Perris near Riverside. At the Tehachapi Mountains, giant pumps lift the water from the California Aqueduct 2,000 feet over the mountains and into southern California.

The SWP provides irrigation water to farms in the San Joaquin Valley, and is a major source of supply for cities in Los Angeles, Riverside, San Bernardino, San Diego, and other parts of southern California. The project is operated by the California Department of Water Resources.

Colorado River

The 1,440-mile-long Colorado River passes through parts of seven states, several Indian reservations and the Republic of Mexico. California is entitled to 4.4 million acre-feet of water annually from the river. Most of that water irrigates crops in the Palo Verde, Imperial and Coachella valleys, located in the southeastern corner of the state, but the Colorado also is a vital source of water for urban Southern California. Urban supplies are distributed by the Metropolitan Water District (MWD) of Southern California through its Colorado River Aqueduct. MWD is a water wholesale agency that supplies water to water districts that serve 18 million customers in Los Angeles, Orange, San Diego, Riverside, San Bernardino and Ventura counties.

Los Angeles Aqueduct

Aqueducts built by the City of Los Angeles draw water from the Owens River, Mono Lake Basin and reservoirs on the east slopes of the southern Sierra. In Los Angeles, a 223-mile aqueduct completed in 1913 has served as a major water supply source, conveying water from the Owens River in the eastern Sierra. A second aqueduct, completed in 1970, added another 50 percent capacity to the water system. The two aqueducts deliver an average of 430 million gallons a day to the city.